There have been low-rise buildings, for example, steel houses, in which various members of thin light-gauge shaped steel formed by roll-forming thin steel sheet having a thickness of less than 2.3 mm are used as structural frames, floor joists or roof members and joined with fasteners.
In the conventional steel house, when a subsidiary roof 2 is attached to a main roof 1 for the purpose of providing a main entrance as shown in FIG. 1(a), the main roof 1 is constructed by extending truss upper chord members or rafters 5 from a ridge 3, while the subsidiary roof 2 is constructed by extending rafters 6 from a ridge 4 to the intersection; i.e., a valley line 7; between the main roof and the subsidiary roof. Further, as the joining portion of the truss upper chord member or the rafter 5 with the valley line 7 is oblique to the latter, as shown in FIG. 1(b), it is impossible to directly join them with each other. To solve such a problem, a channel bracket 8 is disposed between the rafter 6 and the upper chord or the rafter 5 to cover the truss upper chord or the rafter 5 and fixed thereto by bolts or screws, and a plate bracket 9 is fixed to a tip end of the rafter 6 by bolts or screws, as shown in FIG. 1(c).
As described above, the prior art is problematic in that the number of parts increases, the site work requires a great effort since the truss upper chord member or the rafter 5 and the rafter 6 are joined together at many points, and it is difficult to neatly represent the valley line and join the subsidiary roof building with a high accuracy.
As shown in FIG. 3, to join the roof truss upper chord members or the rafters with a wall, a reinforcement member 22 is bridged as a cleat member between the truss upper chord members or the rafters 20-1, 20-2 on the upper surface of the wall 21 in a region in which the roof truss upper chord members or the rafters 20-1, 20-2 intersect the wall 21, so that the opposite ends of the cleat member are fixed to flange portions of the truss upper chord members or the rafters 20-1, 20-2 by means of cleat brackets 23, 23. Also, a saddle bracket 24 may be attached to the intersection between a side surface of the roof truss upper chord member and a surface of the wall 21 to fix the both with each other. According to these construction methods, however, there is a problem in that not only the number of parts or brackets and the material cost to make them increase, but also the working time necessary for attaching them at the construction site becomes enormous.
In addition, as shown in FIGS. 6(a) and 6(b), two roof truss upper chord members or rafters are joined together at tops thereof via top cleat members even though the roof truss upper chord members or rafters are adjacent to each other. During this joining, many parts such as top bracing members, brackets, lip channels, angles or others must be accurately coupled and joined, which is problematic because the number of parts is excessively large as well as considerable effort is necessary for the assembly thereof.
The present invention has been made to solve the above-mentioned problems by providing a structure for joining a subsidiary roof with a main roof, particularly to a structure for joining a truss upper chord member or a rafter of a main roof with a rafter of a subsidiary roof, wherein a metal hanger formed by bending a thin steel sheet is disposed on a valley line. Also, the present invention provides a structure for joining a roof truss upper chord member or a rafter with a wall, wherein a joining portion in which a cleat member or a saddle bracket is necessary in the prior art is fixed by a metal fixer formed by bending a thin steel sheet. Further, the present invention provides a structure for joining roof truss upper chord members or rafters adjacent to each other, wherein a thin steel sheet member and a box-shaped bracket formed by bending a thin steel sheet are fixed to the join between the roof truss upper chord members or the rafters to join a top cleat member.